2004/09/30 by Shinji Tsujikawa, M. Sami · 4 citations
Physics and Astronomy · #Advanced Differential Geometry Research #Astrophysics #Barotropic fluid #Black Holes and Theoretical Physics #Cosmology #Cosmology and Gravitation Theories #Dark energy #Equation of state #Mathematical physics #Physics #Quantum mechanics #Quintessence #Scalar (mathematics) #Scalar field #Scaling #Tachyon #Theoretical physics #astro-ph #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1016/j.physletb.2004.10.023
published as Phys.Lett.B603:113-123,2004 · 7 pages, no figures, references updated; final version to appear in PLB
arxiv created 2004/10/18 · openalex publication_date 2004/10/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Our ignorance about the source of cosmic acceleration has stimulated study of a wide range of models and modifications to gravity. Cosmological scaling solutions in any of these theories are privileged because they represent natural backgrounds relevant to dark energy. We study scaling solutions in a generalized background H2 ∝ ρTn in the presence of a scalar field \vp and a barotropic perfect fluid, where H is a Hubble rate and ρT is a total energy density. The condition for the existence of scaling solutions restricts the form of Lagrangian to be p=X1/ng(Xenλ\vp), where X=-gμν ∂μ\vp ∂ν\vp /2 and g is an arbitrary function. This is very useful to find out scaling solutions and corresponding scalar-field potentials in a broad class of dark energy models including (coupled)-quintessence, ghost-type scalar field, tachyon and k-essence. We analytically derive the scalar-field equation of state w_\vp and the fractional density Ω_\vp and apply it to a number of dark energy models.